Drying and gas or vapor contact with solids – Material treated by electromagnetic energy – Ultraviolet energy
Reexamination Certificate
2002-05-22
2003-09-23
Wilson, Pamela A (Department: 3749)
Drying and gas or vapor contact with solids
Material treated by electromagnetic energy
Ultraviolet energy
C034S276000, C034S378000, C034S420000, C034S428000, C438S707000, C438S715000, C438S769000
Reexamination Certificate
active
06622398
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is manufacturing of semiconductors.
BACKGROUND OF THE INVENTION
Semiconductor devices, such as micro-processors, memory chips, and various other electronic devices are manufactured using well-known techniques. These types of electronic devices are typically manufactured from silicon or gallium arsenide wafers, although other materials may be considered as well. Additional electronic products, such as flat panel displays, rigid disk memories, thin film head device substrates, compact disk substrates, etc. are manufactured using similar techniques. These articles are collectively referred to as semiconductor articles.
In manufacturing semiconductor articles, the base materials, such as silicon wafers, are often exposed to various chemicals, to add or remove layers of material; to change the characteristics of the base material; for cleaning; or for other purposes. These processing steps are often carried out by spinning the semiconductor articles within a processing chamber. Liquid and gas phase chemicals are sprayed onto, or otherwise applied to, the semiconductor articles in the processing chamber. After a predetermined time, the liquid processing chemicals are drawn off and out of the chamber, usually at the bottom of the chamber, while the gases and/or vapors, are separately drawn or pumped out of the chamber and then vented to the outside.
For certain processing steps, a high concentration of ozone is introduced into the processing chamber, typically for a brief interval of e,g., 5-20 seconds. The ozone is then removed from the processing chamber (typically along with other chemicals, such as acid vapors) and then exhausted to the atmosphere.
However, ozone is a highly chemically reactive gas. In high concentrations, it can become toxic to humans. The exhaust mixture of ozone and acid vapors can therefore be both toxic, and highly corrosive. Consequently, handling the gas exhaust from a processing chamber may require special procedures. For example, components such as ducts, etc. generally must be made of polypropylene or other plastics which resist corrosion. Leak detectors may also be employed to detect any leaks in the pipes or ducts carrying the exhaust gases from the processing chamber to the outside.
In addition, ozone is typically produced using electrical corona discharge equipment, which makes O
3
from oxygen O
2
. While ozone can be made from the oxygen in air, ozone production can be increased using concentrated oxygen (e.g., from bottled oxygen gas), although this increases manufacturing costs. Similarly, in semiconductor processing methods where acid vapors are exhausted to the atmosphere, the acid must be replenished, adding to manufacturing cost.
Accordingly, it is an object of the invention to provide an improved apparatus and method for processing semiconductor articles.
SUMMARY OF THE INVENTION
In a first aspect of the invention, a machine for processing semiconductor articles has an ozone remover connected to a processing chamber. As outflow gases including ozone flow out of the processing chamber and into the ozone remover, the ozone is destroyed. The level of ozone in the outflow gases conducted and released to the outside, is reduced.
In a second aspect of the invention, the ozone remover has an ultraviolet light source providing ultraviolet light into a light chamber. Ozone in the outflow gases flowing through the light chamber is converted into oxygen via the ultraviolet light. Preferably, the outflow gases travel in a flow path through the light chamber surrounding the ultraviolet light source. An ozone detector is advantageously provided to switch on the ultraviolet light source when ozone is detected in the ozone remover.
In a third and separate aspect of the invention, a recirculation line is provided to reduce or eliminate release of outflow gases from the processing chamber to the outside environment. A diverter advantageously diverts the outflow gases and vapors from the ozone remover into a recirculation line, during specific processing cycles, or when the presence of certain chemicals is detected in the gases. Oxygen in the recirculation line, created by exposing ozone to UV light in the ozone remover, and any residual ozone in the recirculation line, is optionally separated from other gases or vapors in the recirculation line, and recycled to an ozone source.
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Perkins Coie LLP
Semitool Inc.
Wilson Pamela A
LandOfFree
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